The Police Ombudsman has found that police were justified in using CS Spray to separate rival Loyalist factions during serious hand-to-hand fighting in Londonderry/Derry's Tullyalley estate.
Up to 80 people, some armed with knives and pick axe handles, were involved in the clashes, which happened shortly after 1am on 15 August 2004.
Groups of 20 to 30 people arrived from different directions and fights broke out in different areas of the estate. Police believed the fighting was between elements of the UDA and UVF.
At one stage a man was knocked unconscious after being kicked and punched around the head and body by up to six other men. A police officer was punched on the jaw when he intervened.
A woman was also punched when she ran towards a crowd coming into the Milltown View area from the Ardmore Road direction.
Initially only nine police officers were available to deal with the disturbances, although reinforcements arrived at the scene quickly.
One officer recalled spraying a man who approached police aggressively having failed to heed a warning to stand back. The officer then used the spray against two men who were fighting, and against three other men who aggressively approached police lines.
Another officer discharged up to seven bursts of CS Spray to break up fights and prevent assaults on police officers. When his spray ran out, he was forced to use his baton to strike a man on the lower legs to break up a fight.
A female police officer drew her CS Spray when she noticed members of the crowd trying to get behind police lines. The crowd kept back when she broke the seal on her CS Spray and she did not need to use it.
The discharges happened during the six month period following the introduction of CS Spray to Northern Ireland - a period during which the PSNI had requested that all discharges should be independently investigated by the Police Ombudsman's Office.
During their investigation, Police Ombudsman investigators examined all relevant PSNI documentation and witness statements from the officers involved.
They also carried out house-to-house enquiries, sought CCTV footage and made enquiries at local hospitals for anyone suffering the effects of exposure to CS Spray, but these enquiries produced no new evidence.
The officers' training records were also examined and it was established that they had been properly trained and qualified to carry the spray.
Having considered the evidence, the Police Ombudsman, Mrs Nuala O'Loan, said the fighting had posed "a genuine threat to life" and said use of CS Spray was "a proportionate and justified response".
"Given the sheer numbers they faced and the severity of the violence, the officers were in real danger - as were other members of the public. The officers' actions were both brave and reasonable," added Mrs O'Loan.